Characterization and quantitation of foreign substances, secretions and cells which accumulate in airways and interstitium of persons exposed to foreign inhalants and who develop impaired pulmonary function is in progress. Identification of the environmental source of these inhaled inflammagens is being investigated. The toxic effect of these accumulated materials, which are largely silicious, on isolated alveolar macrophages, cultured Type II cells and pulmonary fibroblasts are in progress.